LPB (AM and FM) I used an AM LPB at the radio station I worked at.

Decade (FM) I've heard this one on the air too.

Radio Systems (Phase II series transmitters, I think)

Catel

Marble "Skycaster" units ...only heard about them.

If you can tell me anything on these or other units, let me know please.

It's called the model FM-100 Super Pro FM Stereo transmitter kit ($249.95) and has a companion transmitting antenna called the model TM-100 True Match FM Antenna Kit ($39.95).

I built one in about 8 hours and it's a real professional unit with stereo line level inputs and a mike input for paging! It seems to be very stable and has good limiting free from distorion or frequency drift. The transmitting frequency is the range of standard FM broadcast band 88-108 mhz and you can program the frequency by going into test mode and holding the up/down buttons till you see the freq you want on the digital display. It has eeprom memory to hold frequency without need of battery backup. With the TM-100 antenna it covers the drivein field quite nicely.

It's worth a try if you like building things (or known a tech who could assemble it for you).

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There's some used broadcast gear at Harris' site: http://www.broadcast.harris.com/used-eq/

I guess if you were going to have the Cadillac of drive-ins w/FM sound, you'd have a good old analog Orban Optimod! Probably for most ears, a less expensive consumer expander/compressor/limiter in a standalone or multi-effects rack box from a guitars-n-drums music store would work OK. Set it for least compression on a passage w/what you'd consider "normal" level, & let it just crush the screaming trailers down. Those trailers are so compressed already in production, it should hardly be noticed.

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I use it at our church on occassions to broadcast the worship services from the santuary down to the other end of the building to the nursury workers, and I've used it several times with my mobile DJ system.

When we open our drive-in, I'd prefer to use a rack mount model similar to the Decade, or the Skymaster.

I've got an AM transmitter too, but haven't quite yet figured how to hook it up. It's two big bulky "cubes" (about 8" x 8" x 6")that mount on the wall. (I believe it says "LPB Cinematronics" on the name plate)

Drive-In patrons are different type of folks from what I've been able to see. They don't really care about 7 channel surround sound - SDDS, DTS or THX approved systems. Most of the drive-in patrons are there to "experience the drive-in" - not to experience the sound systems. Today's remaining drive-ins are very limited with their abilities to deliver the soundtrack to the customer, something that you "indoor guys" will never have to worry about.

LPB is located in Canoga Park, Calif. Here's their phone number: (818) 340-4590

Is your LPB white? Either you have 2 transmitters or you have a transmitter and a coupler (Carrier Current). The carrier current setup superimposes the AM radio signal on the existing field speaker wires for its antenna. This system assumes your field wiring to be in excellent condition (no shorts, breaks, or leaks to ground) otherwise you'd blow the transmitter.

You can rack mount the Ramsey FM-100, just buy a 2U high "rack mount shelf" which is the same thing people do to rack mount their CD players for intermission music.

The Ramsey FM-100 is MUCH better than any of their low-end transmitters. You've got to see all the stuff that goes inside it.

In the USA, doesn't the FCC Regulations Part 15 still limit the power and distance of transmissions in the FM and AM broadcast bands? Radiating about 3/4 mile is likely to get some complaints from people having interference on their radios, or upset with their young kids listening to "bad language" movies from the nearby drive-in.

Way back in the late 1960's, when I worked at the Grandview Drive-In, a neighboring conservative church group got on our case when we played the R and soft-X movies in the off season, and teenagers would park next to the lot when they were turned away at the boxoffice.

The Ramsey kit meets Part 15 requirements for low power FM. The export version of it is equipped with a 5 watt "booster" module installed (you could transmit across town with that one).

The FM-100 puts out about 50 MILLIWATTS (if I remember right, I don't have the manual in front of me). Surrounding terrain, antenna height, antenna placement, and having a metal fence around the theater all affect the distance the signal will travel and reception quality. If the transmitted signal is TOO strong, you can always find a way to reduce it. Remember there are alot of driveins with no neighbors near them.

At the Skyline drive in here in Shelton, we have an old LPB AM mono transmitter with a carrier current coupler into the field speaker wires. To the right of the theater is a couple of 100 acre farms and to the left of the theater is a used car dealer and a gas station. The theater is built on a hillside with a WOODEN fence around most of the property (except for a chain link fence along the back). Carrier Current isn't suppossed to transmit far, but I think being on a hillside must make our system like an "antenna farm" because I can hear our radio signal a mile down the road at the Indian casino before it fades out to nothing.

With that much range, you'd probably need the whole gate/expander/compressor/limiter bit. The expander would pull up suiet sounds you'd need, & the gate would keep out Whatever else is down there.

Boxes like that used are usually all over pawn shops & rock-n-roll music stores, & with even less compression than most radio stations use I'll bet it would make a big difference in ease of listening to movies on a car radio.

Or find an old CBS Volumax & plug it in for the classic pumping & slamming early top 40 radio sound, if you have a sense of humor & no conscience or mercy. Everything will sound like an action movie trailer, & the folks in the cars will grow exhausted & homicidal.